Ultra Wideband (UWB) receivers face unique challenges in signal reception due to low signal levels, high signal frequencies, and the like associated with the UWB signal environment. In particular, given that, for reasons understood in the art, UWB receivers are configured to rapidly and accurately process low power, high speed incoming analog signal components, an exemplary UWB receiver is configured with several receiver fingers each finger processing a version of the incoming signal. Each finger is capable of locking on a signal version and independently processing components of the signal including the signal preamble and the like. If a signal recovered from a particular receiver candidate finger possesses superior signal characteristics, such as superior signal-to-noise ratio or the like, that finger is chosen to process the signal. Likewise, if during processing on the new finger, a different candidate finger exhibits still better characteristics, such as a superior signal to noise ratio compared to the currently selected finger, the second new finger may be chosen for processing.
During processing, a signal associated with a successful candidate finger will be processed including recovering a clock from the signal and information in the form of, for example, a data packet will be recovered associated with the clock. On other fingers, a clock and data will also be recovered associated with the signal however the clock and data will often be slightly offset from the versions recovered from other fingers. In particular, the versions of the recovered clock from each of the fingers will often be phase indeterminate in comparison to each other. Still further, the data associated with each of the fingers may be offset in time by several data segments. One of the recovered clocks associated with the currently selected finger is used within the receiver circuit to clock data through receiver circuit sections and into the digital processing modules.
It will be appreciated that when a receiver is processing an incoming signal from one finger, and determines that a switch to another finger is advantageous, challenges can arise when the switchover is conducted, particularly when the clock switchover is conducted and the clocks are shifted in phase relative to each other. If the state of the clock of the currently selected finger does not match the state of the clock associated with the candidate finger being switched to, glitches in the clock state can occur during the switchover. Since the recovered clock is used within the receiver to process data through the receiver, such glitches are undesirable in that they can cause data loss, loss of receiver synchronization, can cause the receiver registers to enter into an undefined or indeterminate state, and can give rise other potentially more serious problems. To further complicate the clock switchover scenario, data streams associated with the receiver fingers may be slightly offset from one another resulting in a packet loss or other, potentially worse consequences when the switchover occurs.
Thus it would be advantageous for a receiver to be capable of providing a smooth transition between clocks when switching from processing on one receiver finger to another or when switching between any clock sources. Such a receiver could be more simply constructed and could reduce the likelihood of dropped packets, loss of synchronization, and the like.